The present invention relates to a method for generating an electric power and a battery utilizing a sugar as a source of energy.
Like protein and lipid, sugar is an important energy source for animals. Glucose represented by the chemical formula: C6H12O6 is a typical example of a sugar. When one glucose molecule is completely oxidized, 24 electrons are taken out of it, and carbon dioxide and water are produced. These 24 electrons are utilized as energy in the body of any animal. According to the thermodynamic calculation, glucose has an energy of 2872 kJ per mol or 4.43 Wh per gram. This energy density is higher than 3.8 Wh/g, which is the weight energy density of metallic lithium used for the negative electrode of a lithium battery known to have a high energy density.
However, the methods of utilizing the energy of sugar, have not been developed so far except methods utilizing it as heat energy source through combustion thereof in air or as chemical energy source used for ATP or the like through the action of 10 or more oxidases in an animal body (see Alberts et al., Essential Cell Biology, Garland Publishing, Inc. 1997, p107). Specifically, no method have been produced of effectively utilizing the chemical energy of sugar directly as electric energy.
In view of the foregoing circumstances, it is an object of the present invention to provide a method for generating an electric power, which allows efficient utilization of a sugar as an energy source.
It is another object of the present invention to provide a battery, which allows efficient utilization of the chemical energy of a sugar directly as an electric energy.
The present invention is directed to a method for generating an electric power by generating an electromotive force between a positive electrode and a negative electrode with an electrolyte intervening therebetween, comprising a process of electrolytic oxidation of a sugar on the negative electrode, the-oxidation being associated with cleavage of at least one carbon-carbon bond of the sugar.
Preferably, the electrolytic oxidation comprises a step of forming a coordination compound comprising the sugar.
The negative electrode preferably has a component capable of forming a coordination compound with the sugar via a hydroxyl group thereof.
The above component is preferably carried on a conductive substrate which constitutes the negative electrode.
It is preferable that the above component comprises a metal element capable of forming an amphoteric hydroxide.
It is also preferable that the metal element is at least one selected from the group consisting of Mg, Ti, V, Ni, Cu, Zn, Zr, Ag, In, Sn, Sb, and Pb.
It is further preferable that the above component comprises at least one selected from the group consisting of lead oxide, lead hydroxide, and basic lead carbonate.
The conductive substrate constituting the negative electrode preferably comprises a metallic lead or a lead alloy.
The conductive substrate further preferably comprises a lead alloy which contains at least one selected from the group consisting of Mg, Ti, In, Sn, and Sb.
The present invention is also directed to a battery comprising a positive electrode, a negative electrode, an electrolyte intervening between the positive electrode and the negative electrode, and a sugar to be supplied to the negative electrode. In this battery, the negative electrode is capable of promoting an electrolytic oxidation of the sugar thereon to generate an electromotive force between the positive electrode and the negative electrode, the electrolytic oxidation being associated with cleavage of at least one carbon-carbon bond of the sugar.
It is preferable that, in the battery, the negative electrode has a component capable of forming a coordination compound with a sugar via a hydroxyl group thereof. Herein, the component is preferably carried on a conductive substrate constituting the negative electrode.
In the battery, the component preferably comprises at least one selected from the group consisting of lead oxide, lead hydroxide, and basic lead carbonate. Further, the conductive substrate constituting the negative electrode preferably comprises a metallic lead or a lead alloy.
It is preferable that, in the battery, the positive electrode is capable of promoting an electrolytic reduction at a higher electric potential than the electrolytic oxidation on the negative electrode.
The positive electrode is preferably an oxygen electrode capable of reducing oxygen.